Answer:
aₙ = 9n - 31
Step-by-step explanation:
If we call the common difference as d, since 19 - 7 = 12, we can write:
32 + 12d = 140
12d = 108
d = 9 which means that a₁ = a₇ - 6d = 32 - 6 * 9 = -22.
Explicit formula for arithmetic sequence: aₙ = a₁ + (n-1)d so the answer is
aₙ = -22 + (n - 1) * 9
= -22 + 9n - 9
= 9n - 31
